There is information about Colossus: the original GFS paper, an interview with Sean Quinlan with McKusick on Colossus improvements, as well as a talk by Denis S

There is information about Colossus: the original GFS paper, an interview with Sean Quinlan with McKusick on Colossus improvements, as well as a talk by Denis Serenyi on more of the gory details, e.g. rebalancing. There was also a public talk on D, the GFS chunkserver replacement, but there don't seem to be recordings or slides from that.